This invention relates to a battery-powered, hand-guided power tool, and in particular to a hammer, in which a rechargeable battery pack is releasably connected to a tool housing of the hammer via a rail-and-channel structure, and the battery pack is locked in an operative position on the tool housing in which electrical contacts of the battery pack and associated electrical contacts of the power tool are electrically connected along a contact length extending in the direction of a longitudinal extent of the rail-and-channel structure.
A power tool, such as a drilling hammer, is disclosed in German Patent Publication No. DE 195 21 423 (A1) and includes a tool housing. The tool further includes a rail-and-channel structure which is formed on a side portion of the tool housing and extends on a front side of a portion of the housing. The tool housing is also formed with a rear hand grip substantially at right angles to a longitudinal axis of a tool holder supported at the front of the tool. A spring-loaded latch element is located in a lower part of the hand grip, which, when in a locking position and with a battery housing assembled with the tool housing, engages in a latch recess of the battery housing to thus hold the battery pack in its operative position on the tool housing. The latch element is accessible through an opening at the lower end of the hand grip, so that a user may move the latch element, manually against the force of a compression spring, out of the locking position and into a release position.
With structure disclosed in German Patent Application No. DE 195 21 423, a user has to hold the power tool with one hand and use the other hand to move the latch element into a release position to release the battery pack. If, in so doing, the user has oriented the power tool so that the battery pack is able to come free of the power tool under gravity, there is a risk that the battery pack, which the user is unable to hold at the same time, will drop out in an uncontrolled manner, which can lead to damage to the battery pack and perhaps even to injury. If, on the other hand, the user holds the power tool oriented so that, as the latch element is displaced, the battery pack is supported on the portion of the housing forming the hand grip, that is, with the tool holder axis directed upwardly, the battery pack will not move from its position as the latch element is drawn back. When the latch element is subsequently released, it will again enter the latch recess of the battery pack, so that the battery pack continues to be connected to the power tool.
Also, with the structure disclosed in German Patent Application No. DE 195 21 423, if the user inserts the battery pack in the last position mentioned, the electrical contacts of the power tool and the battery pack may come into contact, but the latch element may, unnoticed, fail to lock in the latch recess. Although the power tool can be operated in this position, the battery pack will suddenly become detached from the power tool when this is inclined at a relevant angle, the surprise effect in particular of such an occurrence possibly leading to injury to the user or even to other persons, for instance, if the power tool is being used on a construction site.
Therefore, it is an object of this invention to construct a power tool such that, with greater safety in use, the battery pack can be moved in a simple manner out of its operative position.
With this and other objects in mind, this invention contemplates a battery-powered, hand-guided power tool in which a rechargeable battery pack is releasably connected to a tool housing. A rail-and-channel structure is formed with a longitudinal extent between opposite ends thereof, for facilitating the assembly of the battery pack in an operative position on the tool housing. A locking device, including a latch structure, is located on the housing for locking the battery pack with the housing in the operative position, and includes a latch structure which is locatable between a device latched position, coincidental with the operative position of the battery pack, and a device release position. A plurality of electrical battery contacts are located on the battery pack, and a plurality of electrical tool contacts are located on the tool housing. The battery contacts and the tool contacts have a prescribed contact length along which they electrically engage. The battery contacts and the tool contacts extend in a direction along the longitudinal extent of the rail-and-channel structure, and are electrically connected when the battery pack in is the operative position. The battery pack is movable from the operative position into a battery release position when the latch structure is moved from the device latched position to the device release position to permit the battery pack to be moved in the direction of the longitudinal extent of the rail-and-channel structure for removal from the tool housing. A spring is located on the tool housing and positioned to apply a spring-loaded force to the battery pack in the operative position in a direction of a displacement movement of the battery pack out of the operative position. The spring is expandable by a distance greater than the prescribed contact length, and the restoring force of the spring when extended to the prescribed contact length is greater than the weight of the battery pack.
Other objects, features and advantages of the present invention will become more fully apparent from the following detailed description of the preferred embodiment, the appended claims and the accompanying drawings.